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Using density functional theory (DFT) computations, we investigated pyridinelike structures in a series of single-walled CN(x) nanotubes and found that tube chirality and diameter play important roles in the formation of pyridinelike structures. Not pyridinelike structures but more N(C) defects (N atoms substituting for C atoms) should be responsible for the experimentally observed donor states of CN(x) nanotubes. The adsorption energies of Li at the pyridinelike defect are so large and the energy barrier for lithium penetrating the defect is so low that CN(x) nanotubes with pyridinelike structures have enhanced capability for lithium storage.

The dramatically increasing demand of high‐energy lithium‐ion batteries (LIBs) urgently requires advanced substitution for graphite‐based anodes. Herein, inspired from the extra capacity of lithium storage in solid‐electrolyte interface (SEI) films, layered hydroxide cobalt acetates (LHCA, Co(Ac)0.48(OH)1.52·0.55H2O) are introduced as novel and high‐efficiency anode materials. Furthermore, ultrathin LHCA nanoplates are face‐to‐face anchored on the surface of graphene nanosheets (GNS) through a facile solvothermal method to improve the electronic transport and avoid agglomeration during repeated cycles. Profiting from the parallel structure, LHCA//GNS nanosheets exhibit extraordinary long‐term and high‐rate performance. At the current densities of 1000 and 4000 mA g−1, the reversible capacities maintain ≈1050 mAh g−1 after 200 cycles and ≈780 mAh g−1 after 300 cycles, respectively, much higher than the theoretical value of LHCA according to the conversion mechanism. Fourier transform infrared spectroscopy confirms the conversion from acetate to acetaldehyde after lithiation. A reasonable mechanism is proposed to elucidate the lithium storage behaviors referring to the electrocatalytic conversion of OH groups with Co nanocatalysts. This work can help further understand the contribution of SEI components (especially LiOH and LiAc) to lithium storage. It is envisaged that layered transition metal hydroxides can be used as advanced materials for energy storage devices.

As substitutions for transition metal oxides (MOs), transition metal carbonates (MCO3) have been attracting more and more attention because of their lithium storage ability in recent years. Is MCO3 better than MOs for lithium storage? To answer this question, monodisperse CoCO3 and CoO microspindles with comparable structures were synthesized and investigated as a case study. Excluding its structural effect, we found CoCO3 still exhibited reversible capacities and rate capabilities much higher than those of CoO. The reversible capacity of CoCO3 after 10 cycles was 1065 mAh g(-1), 48.2% higher than that (∼720 mAh g(-1)) of CoO. Furthermore, the greatly different electrochemical behaviors were investigated by analyzing the discharge-charge profiles, cyclic voltammetry curves, and Nyquist plots in depth. This work can improve our understanding of the lithium storage advantages of MCO3 against MOs and enlighten us in terms of developing high-performance MCO3 with favorable structures.

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